Maybe in the UK it's different, but in other countries motive is very relevant.

Getting approached while being filmed and cheekily asked "are you a bad man?" Before getting stabbed would be very relevant in multiple places, both Finland, Mexico, El Salvador, and USA, for example, because it would indicate it was not premeditated murder and instead "crime of passion" and in some cases, "crime of instigation".

I've been curious about what led up to it not because of legality however, but because of morality.

I don't think it's moral to stab someone over this. But I understand now why someone was stabbed over this. And most importantly, it's not just a random stabbing, but one that was instigated by the victim, which could have been avoided by not being an asshole. It's unfortunate he couldn't learn the lesson in a way that resulted in his life coming to an end, and more unfortunate still that the police didn't act professionally and try to save his life, although apparently a pathologist said it would have been unlikely be would have survived that wound.

Thankfully these details were provided by another comment with a link.